Occurrence of Bacterial Leaf Streak on Maize (Zea mays) in Adamawa State, North East Nigeria

Bacterial leaf streak of maize, caused by Xanthomonas vasicola pv. vasculorum, is an emerging disease that has been gaining attention across sub-Saharan Africa, though its prevalence in Nigerian maize systems remains incompletely characterised. This study investigated the occurrence and distribution of bacterial leaf streak in maize farms across four agricultural zones in Adamawa State during the 2023 growing season. Field surveys encompassed 65 farms, with disease incidence and severity assessed based on the proportion of infected plants and the extent of leaf streaking observed. Symptomatic samples were collected and subjected to biochemical tests and polymerase chain reaction assays targeting the X. vasicola pv. vasculorum species-specific hrp gene cluster. Bacterial leaf streak was confirmed in 29 percent of surveyed farms, with higher concentrations in valleys and lowland areas receiving higher rainfall and frequent dew deposition. Leaf streaking was observed from early vegetative stages, suggesting early-season infection via infected seeds or splash-dispersed inoculum. Growers in the survey area were largely unaware of this bacterial disease, associating streak symptoms with fungal leaf spots or nutrient disorders. The study adds novel distributional data for X. vasicola pv. vasculorum in North East Nigeria and highlights the need for expanded diagnostic capacity and seed health testing in the region. Keywords: maize, bacterial leaf streak, Xanthomonas vasicola, Adamawa, disease occurrence.